Switching mechanism



Jan. 1940- G. c. VAN DUSEN, JR 2,188,635

SWITCHING MECHANISM Filed Jan. 2, 1937 r Jflvefitor E9 4 7 George 0. Varzpasen Jr Attorrugy' Patented Jan. 30, 1940 SWITCHING MECHANISM George 0. Van Dusen,

signor to Jr., Excelsior, Minn, as-

Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 2, 1937, Serial No. 118,713

Claims.

This invention relates to switching mechanism and more particularly to that type of switching mechanism wherein a mercury switch is utilized to make or break a circuit to control suitable a apparatus in response to variations in the value of a condition.

A principal object of this invention is the provision in a switching mechanism embodying a mercury switch of means whereby the mercury switch may be centered accurately with respect to the instrument, such centering being substantially permanent with respect to each instrument whereby the switch may be readily replaced without the necessity for further cenl6 tering of the replacement switch.

An additional object is the provision of a structure wherein the mercury switch may be readily replaced by unskilled persons and the replaced switch will be centered in the identical 2 mannercf the original switch. a

As conducive to a clearer understanding of this invention it may here be pointed out that in switching mechanisms of the type to be hereinafter described, it is essential that the switch be so positioned withvrespect to the instrument that when the instrument is in its desired position and properly aligned the circuit through the mercury switch will either be made or broken as the case may be at a substantially equal dis- '0 tance upon each side of the horizontal plane of the instrument. This factor is well known in the art and hitherto it has been common practice to center each switch individually in the instrument in the factory before placing the a same on the market. Various expedients have been utilized to accomplish this, the more common being to provide a clip for the mercury switch movable with respect to the tiltable support and provide an eccentric to vary the respective positions of the clip and the support whereby the switch may be centered subsequent to the mounting thereof in the instrument. This method has proved satisfactory in factory assembled switches, its chief disadvantage being that when, as frequently occurs, it is necessary to replace a damaged mercury switch after the instrument has left the factory, the centering of the replaced switch is placed in the hands of an unskilled person and'is, accordingly, frequently so improperly done with resultant improper operamay be centered and upon the necessity of replacement thereof, an additional switch and support therefor, factory assembled, may be readily installed and centered substantially automatically, the previous centering in the factory being so arranged as 'to readily accommodate the replacement switch and clip.

Other objects will in part be obvious and in part pointed out hereinafter.

The invention, accordingly; consists in the combinations of elements, arrangements of parts and features of construction, all as will be pointed out more fully. hereinafter and disclosed in the accompanying drawing.

Having reference now to the accompanying drawing:

Figure 1 is a front elevational view of one form of switching mechanism disclosing an illustrative embodiment of the invention;

Figure 2 is an enlarged fragmentary view disclosing certail details of construction;

Figure 3 is an enlarged sectional view taken along the line 3-3 of Figure 2 as viewed at an angle from the left;

Figure 4 is a front elevational view of a switching mechanism embodying a modification of the invention, certain parts thereof being cut away and certain others being omitted, and

Figure 5 isv an enlarged sectional view taken along the line 55 of Figure 4 as viewed from the bottom.

Similar reference characters refer to similar parts throughout the several views of the drawing.

Referring now to Figure 1, there is generally indicated at ID a casing to the lower portion of which is secured, as by screws H, a housing l2 which contains a conventional Sylphon bellows (not shown). A suitable pressure or capillary tube l3 leads into housing I2 from any suitable source (not shown), the arrangement being such that condition change adjacent the said source causes expansion or contraction of the Sylphon bellows in a known manner to produce upward or downward movement of an operating rod I4. Operating rod 14, in turn, abuts an end of a lever l5 which is iucrumed on a knife edge [6. A spring I! suitably secured to lever l5 biases the same in a direction opposite that of the pressure exerted by operating rod I4. Spring I1 may be adjusted as by a screw l8 in a. known manner to vary the value of the condition at which the device will operate. A second lighter spring I9 issecured to a member 20 pivoted as at 2| and provided with an extension .22 which, in turn, abuts an end of lever I5 and is adjustable as by a screw 22 to vary the operating differential of the instrument, also in a known manner. 55

Suitable indicating pointers 23 and 24 secured to springs II and I9, respectively, extend exteriorly of the casing through suitable apertures (not shown) to indicate the value of the condition required to operate the switching mechanism and the operating difierential thereof upon a suitable scale plate, a side elevation of which is generally indicated at 25.

Lever I5 is provided with a substantially integral upwardly extending portion 21. A mer cury tube switch 30 is carried by a tube clip- 3| in turn secured to a U-shaped bracket member 32 pivotally mounted as on a pivot pin 33. The rear leg of U-shaped member 32 is provided with a substantially vertically extending slot 34 as shown in dotted lines. The structure hereinbefore described is known in the-art and in those constructions hitherto utilized a pin would have been secured directly to extending portion 21 to engage slotted aperture 34 and hence tilt the switch. In the instant invention, however, as better shown in Figure 2, a lever 4|) is pivoted to upwardly extending portion 21 as by a pivot 4|. The upper end of lever 40 carries a pin 42 adapted to engage slotted aperture 34 to tilt mercury switch 30 upon movement of operating rod I4 and hence lever I5 and extending portion 21 in a manner now to be described. Such movement will, of course, result in a variation in the position of pin 42 and hence a resultant tilting of support 32 to tilt switch 30.

As better shown in Figure 3, a pin 50 passes through a suitable aperture in extending portion 21. Pin 50 is provided with an eccentric cam 5| and a threaded extremity 52 provided with a tool engaging aperture 53. Eccentric 5| is positioned within an aperture 54 in lever 49. A suitable washer 55 surrounds pin 50 and is positioned between extending portion 21 and lever 40. A look nut 56 is provided with the threads which are engaged by threaded extremity 52. Thus is will appear that rotation of pin 50 as by the insertion of a tool, such as a screw driver, in slot 53 occasions a corresponding rotation of eccentric 5| in aperture 54 and correspondingly moves lever 40 about its pivot 4| and hence pin 42 to the right or left with respect to extending portion 21 and that such movement results in a slight tilting of mercury switch 30, which, when properly adjusted, results in the proper alignment of the switch.

Accordingly, it will now be seen that once a switch is properly aligned if for any reason the switch should prove defective and replacement is desired, it will be a relatively simple matter to remove the support 32 from pin 33 and replace the support and switch as a unit, and it will correspondingly appear that any similar support and switch applied to the device by mounting on pivot pin 33 will of necessity assume the same alignment as that imparted to the original switch by adjustment of pin 59 and that therefore an inoperative switch may be readily replaced by anyone regardless of their skill merely by positioning a new switch and support on pin 33. Any suitable securing means (not shown), such as a spring clip, may be utilized to hold the switch support in related assembly with pin 33.

Suitable conventional leads 58 and 59 lead from terminals of mercuryswitch 3Il to a terminal block 60 provided with terminals 6| to which may be secured leads (not shown) extending to any suitable apparatus to be controlled by switch 30. A conventional aligned pendulum 62 is pivoted in casing I0 as at 63 in a known manner in order that the instrument may be properly aligned when installed.

Having reference now to that modification disclosed in Figure 4, a refrigeration control having an auxiliary high pressure cut-out is disclosed. In the modification disclosed in this figure, a casing'IIl has secured thereto a housing II, as by screws I2, which housing contains a conventional Sylphon bellows (not shown) which may be actuated in a manner similar to that of the bellows described in connection with Figure 1 to move an operating rod I3 which, in turn, acts on an end of a lever I4 fulcrumed as at I5. A spring I8 similar to spring II biases lever I4 in a direction opposite to that of the pressure exerted by the bellows and a differential adjusting spring (not shown) similar to spring I9 is also provided. Screws I8 and I9 adjust spring I6 and the differential adjusting spring in a manner similar to that described in connection with screws I8 and 22.

Lever 14 is provided with an upwardly extending portion upon which is pivoted a lever 8| as by a pivot 82. Lever 8| is provided with a slot 83 which accommodates a pin 84 rigidly secured to upwardly extending portion 80. Lever 8| also has an angularly disposed portion- 85 positioned for abutment by an end 86 of a pivoted member 87 carried by a pivot 88. The opposite end of member 81 is positioned for abutment by an operating rod 89 in turn actuated by a sylphon bellows or other suitable mechanism (not shown) contained in housing 90 and operated in the i1- lustrative embodiment by a predetermined high pressure or other condition. Lever 8| is also provided with an extending portion 9| to which is secured one end of a strain release spring 92, the other end of which is secured to an end of lever I4.

A mercury switch support is pivotally mounted as on a pivot 96 and carries a mercury 7 switch clip and mercury switch (not shown) similar to clip 3| and mercury switch 30. Support 95 is provided with an elongated slot 91 similar to slot 34. An elongated slot 98 is also provided in lever 8| and, as better shown in Figure 5, has passed therethrough a pin 99 provided with a threaded portion I90 and a head |0|. A look nut I02 is positioned for engagement with threaded portion I00. Thus it will be seen that by loosening lock nut I82, pin 99 may be positioned at any point within slot 98. An alignment pendulum I04 similar to pendulum 62 and utilized for a similar purpose is also provided.

From the foregoing, the operation of the switching mechanism should now be apparent. The device is normally controlled by the condition controlling the bellows contained in housing II and through operating rod I3 and its corresponding movement of lever 14 and pin 99 serves to move the mercury switchsupport 95 and its associated switch to open or closed position in accordance with the value of the condition. It will also be seen, however, that upon the achievement of a predetermined condition value of the condition controlling the bellows contained in housing 90, operating rod 89 acts through pivoted member 87 to move the switch through projection 85 to on or ofl position as the case may be independently of the position of operating rod 13,

spring 92 serving, as above stated, as a strain release to permit such movement without effecting the position of member 80 and lever I4.

In the manufacture of the structure described in connection with the above modification, it will aiso be understood that the mercury switch support 95 and hence its associated switch may be readily centered as in connection with the modification previously described by horizontal movement of pin 99 in slot 98 and upon the achievement of such centering a permanent relationship between pin 99 and slot 91 may be established by a simple tightening of lock nut I02. Once such relationship is established and the device is placed in the hands of the ultimate user, should the mercury switch fail for any reason it becomes a relatively simple matter to provide to the user a pre-assembled mercury switch and support identical to support 95 which may be readily replaced merely by removing support 95 from its pivot pin 96 and replacing the same with the new support and assembled switch. The relationship of the parts, it will readily be understood, will be identical to that, previously existing and the new mercury switch will, therefore, be perfectly centered without the necessity of any fine adjustment on the part of the person replacing the switch.

Thus it will be seen that in the above described structures there are provided devices achieving the objects of this invention and others including many advantages of great practical importance particularly with respect to simplicity of assembly and ease of proper replacement of inoperative mercury switches.

As many embodiments may be made of the above described invention and as many modifications may be made in the embodiments above described, it is to be understood that all matter hereinbefore described or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a switching mechanism, in combination, a mercury switch, a support therefor pivoted for rotation, means for rotating said support comprising an operating member, a condition responsive device for operating said operating member, a connecting member pivotally mounted on said operating member and engaging said support, and means for rotating said connecting member with respect to said operating member comprising an elongated slot in said connecting member and a pin rotatably mounted in said operating member and having an eccentrically mounted cam cooperating with said slot.

2. In a switching mechanism, in combination, I

a mercury switch, a support therefor pivoted for rotation, means for rotating said support comprising an operating member, a condition responsive device for operating said operating member, a connecting member mounted on said operating member, a strain release between said operating member and said connecting member, means for moving said connecting member independently of said operating member through said strain release, a slot in said connecting member, a pin mounted in said slot for rotating said support, and means for adjusting said pin along said slot whereby the mercury switch may 1 be properly aligned with respect to said operating member.

3. In a switching mechanism, in combination, a condition responsive means, a member movable thereby, a first lever movable by said member, a second lever pivotally mounted on said first lever, a pin carried by said second lever, a rotatably mounted support having an aperture therein engaged by said pin, "a mercury switch carried by said support, and means to vary the position of said pin with respect to said levers for centering said mercury switch, said means comprising a lock nut on said pin, said pin extending into a slotted aperture in said second lever wherebyby release and tightening of said nut said pin may be moved within the limits defined by said slot and secured in any desired position therein.

4. In a switching mechanism, in combination, a condition responsive means, a member movable thereby, a first lever movable by said member, a second lever pivotally mounted on said first lever, a pin carried by said second lever, a rotatably mounted support having an aperture therein engaged by said pin, a mercury switch carried by said support and pre-assembled therewith to form a substantially integral unit, said condition responsive means serving to rotate said unit through said pin and slot connection, means to rotate said second lever and hence vary the position of said pin with respect to said first lever for centering said mercury switch, and means allowing removal and replacement of said unit, said replaced unit being thus accurately centered in said mechanism.

5. In a switching mechanism, in combination, a condition responsive means, a member movable thereby, a first lever movable by said member, a second lever pivotally mounted on said first lever, a pin carried by said second lever, a pivotally mounted support having an aperture therein engaged by said pin, a mercury switch carried by said support and pre-assembled therewith to form a substantially integral unit, said condition responsive means serving to rotate said unit through said pin and aperture connection, means to vary the position of said pin with respect to said lever for centering said mercury switch, said means comprising a lock nut on said pin, said pin extending into a slotted aperture in said lever whereby by releasing and tightening of said nut said pin may be moved within the limits defined by said slot and secured in any desired position therein, and means allowing removal and replacement of said unit, said replaced unit being thus accurately centered with respect to said mechanism.

GEORGE C. VAN DUSEN, JR. 

